It is not known if the anesthetic agent used to perform ERCP influences the physiologic stress response to the procedure. Anesthesia itself may influence the development of and/or severity of ERCP-induced pancreatitis based on its demonstrated ability to modify the stress response to surgery. This study compares two anesthetic approaches - benzodiazepine and narcotic, or propofol - for potential differences in stress response mediators, such as cytokines, acute phase reactants, glucocorticoids, and prostaglandins. New protocol.